A. Field Of The Invention
The present invention relates to recombinant DNA technology. More specifically, it involves the creation of a cDNA genetic sequence coding for a bovine placental lactogen, a vector containing this gene, and a host containing the cDNA gene.
B. Description Of The Art
The placenta of a cow secretes numerous endocrine signals, including bovine placental lactogen (which is evolutionarily related to growth hormone and prolactin). Naturally produced bovine placental lactogen (also known as bovine chorionic somatomammotropin) has recently been purified and characterized. (See K. A. Eakle et al., Endocrinology 110:1758-1765 (1982); G. S. Murthy et al., Endocrinology 111:2117-2124 (1982); and Y. Arima et al., Endocrinology 113:2186-2194 (1983)) (the disclosure of these articles and of all other articles cited in this patent are incorporated by reference as a fully set forth below.) As described in these articles, at least one (and possibly three) forms of bovine placental lactogen exist.
Bovine placental lactogen promises to have great utility for research and other purposes. For example, it appears to relate to pregnancy development. (See generally C. Schellenberg et al., Endocrinology 111:2125-2128 (1982) (levels change during gestation), or it may stimulate milk production (see U.S. Pat. No. 3,644,925, bovine growth hormone increases milk production.) Still other functions for this protein are likely to be discovered.
Unfortunately, commercial qualities of the protein are not available, and it is prohibitively expensive to extract the protein from natural sources. Thus, it can be seen that a need has existed for a source of large quantities of bovine placental lactogen.